This invention relates generally to an air supply system for firefighting apparatus, and more particularly to a system for supplying compressed air and foam to produce a fire stream comprising an aerated foam.
Air supply systems of the above-indicated type are known and are referred to in the art by the terms CAFS (compressed air foam system) and WEPS (water expansion pumping system). A typical system includes a foam injection system, a water pumping system and an air compressor. When employing mixture ratios of 1 cfm of air to 1 gpm of water, these systems can produce very desirable results in firefighting by the use and application of "Class A" foams to help achieve fire suppression and to deal with increased fire loads and related hazards.
It is the general object of the invention to provide an air supply system of the indicated type including means for driving an air compressor using a split shaft gear box of the type commonly employed on fire trucks. More specifically, the air compressor is mounted on the housing of the gear box in a manner so that a shaft extension of the air compressor is contained in the gear box to be driven by a gear which also drives the fire pump that is also mounted on the fire truck adjacent the gear box.
In accordance with another object of the invention the drive for the compressor is provided with a clutch which allows for the selective use of the compressor.
More specifically, the air supply system in accordance with the invention comprises a rotary vane compressor mounted on the split shaft gear box of the midship pump provided on a fire truck. By this arrangement, compressed air can be introduced into the water stream to make an aerated foam, which foam is more effective as a fire stream than plain water and penetrates faster.
Another feature of the air supply system in accordance with the invention is that by introducing air into the fire hose, the actual weight of the hose is significantly reduced. Thus, it makes handling a 21/2 inch fire hose become a one man job instead of requiring two or three men to handle the hose.
Furthermore, the booster tank provided on the fire truck as a water supply for immediate use at a fire scene can be used over a longer time period since the water supply can be stretched. This makes the fire truck apparatus more effective in that the first fire truck to arrive at a fire scene can be used to apply a fire stream to the fire for a longer time period to limit the fire damage until a subsequent fire truck can be hooked up to the hydrant and supply an additional fire stream.